Gas-barrier films

ABSTRACT

The present invention provides a gas-barrier film which is produced through applying a layer containing a metallic compound to a surface of a processed-polymer layer produced from a mixture of a polyalcohol and at least one poly(meth)acrylic polymer selected from the group consisting of poly(meth)acrylic acids and partially neutralized poly(meth)acrylic acids. The invention also provides a laminated gas-barrier film containing the aforementioned gas-barrier film either surface of which is laminated on with a plastic film. The gas-barrier film exhibits excellent gas-barrier properties and can be produced through a simple, convenient process.

TECHNICAL FIELD

The present invention relates to a gas-barrier film which is producedthrough application of a metallic compound to the surface of a polymerlayer formed from a specific polymer, and more particularly to agas-barrier film which is produced through application of a metalliccompound to a polymer layer formed from a mixture of a poly(meth)acrylicacid polymer and a polyalcohol such as sugar. The present inventionprovides a gas-barrier film which exhibits excellent oxygen-gas-barrierproperties, particularly in an atmosphere of high humidity, and which issuitably used in sterilization treatment such as retorting or boiling.

BACKGROUND ART

Conventionally, in order to enhance gas-barrier properties of plasticfilms, several processes have been proposed. For example, JapanesePatent Application Laid-Open (kokai) No. 9-157406 discloses a process inwhich an inorganic layer compound serving as a filler is incorporatedinto a plastic film, and Japanese Patent Application LaidOpen (kokai)No. 4-366142 discloses a process in which an inorganic compound isdeposited on the surface of a plastic film. In the former process, inorder to enhance gas-barrier properties of a plastic film, a largeamount of inorganic layer compound must be incorporated into the film,and thus properties of a matrix resin, such as transparency andmechanical strength, are impaired. In the latter process, deposition iscarried out at high temperature to form a thin film, and a plastic layermay soften due to heat load, and thus a heat-resistant plastic such aspolyethylene terephthalate, polybutylene terephthalate, polyethylenenaphthalate, or polyimide must be exclusively employed. Also, the latterprocess is disadvantageous in that when a resin of low Young's modulusis employed, gas-barrier properties of a produced film may deteriorate,since the tensile strength of the resin decreases during deposition andthe deposited film is prone to crack.

The latter process is also disadvantageous in that operation iscumbersome and an expensive apparatus is required, since deposition mustbe carried out in a vacuum apparatus. Japanese Patent ApplicationLaid-Open (kokai) No. 8-142256 discloses a moisture-resistant compositedeposition film comprising at least one laminated structure containing apolymer film substrate (A), a deposition film (B) formed of inorganicmaterial which is laminated on at least one surface of the substrate(A), a water-resistant film (C) formed of a sugar and a polycarboxylicacid or a partially neutralized polycarboxylic acid, the film (C) beinglaminated on the film (B); and a polymer composition layer (D)containing a drying agent, such that the layer (D) is provided on atleast one side of the laminated structure. However, the composition filmmay involve drawbacks similar to those as described above, since adeposition film is employed in the composite film. Therefore, there hasbeen demand for a process for producing a gas-barrier film more simplyand conveniently.

In view of the foregoing, an object of the present invention is toprovide a gas-barrier film which can be produced through a simple,convenient process and which exhibits excellent gas-barrier properties.

DISCLOSURE OF THE INVENTION

The present inventors have found that the aforementioned problems can besolved by a gas-barrier film which is produced through application of alayer containing a metallic compound (hereinafter the layer may bereferred to as a “metallic-compound-containing layer”) to the surface ofa polymer layer formed from a mixture of a polyalcohol and at least onepoly(meth)acrylic acid polymer selected from the group consisting ofpoly(meth)acrylic acids and partially neutralized poly(meth)acrylicacids. The present invention has been accomplished on the basis of thisfinding. Japanese Patent Application Laid-Open (kokai) No. 8-224825discloses a gas-barrier laminate which is produced from a plastic filmand a metallic compound. Japanese Patent Application LaidOpen (kokai)No. 58-128852 discloses a laminate exhibiting excellent adhesion, whichis produced from a plastic film and a carboxyl-group-containingpolyolefin film with the intervention of a metallic compound. In theaforementioned laminates, metallic compound layers of continuous phaseare formed through deposition or sputtering.

Accordingly, in a first aspect of the present invention, there isprovided a gas-barrier film which is produced through applying a layercontaining a metallic compound to the surface of a polymer layer formedfrom a mixture of a polyalcohol and at least one poly(meth)acrylic acidpolymer selected from the group consisting of poly(meth)acrylic acidsand partially neutralized poly(meth)acrylic acids. There is alsoprovided a gas-barrier film wherein the surface of the polymer layer towhich the metallic-compound-containing layer is not applied is fixedonto a surface of a substrate. There is also provided a gas-barrier filmwherein at least the polymer layer is subjected to heat treatment. Thereis also provided a gas-barrier film wherein the metallic compound is atleast one species selected from the group consisting of magnesium oxide,calcium oxide, zinc oxide, magnesium hydroxide, calcium hydroxide, andzinc hydroxide. There is also provided a gas-barrier film wherein themetallic-compound-containing layer is produced from a mixture of themetallic compound and a resin. There is also provided a gas-barrier filmfor use in sterilization treatment.

In a second aspect of the present invention, there is provided alaminated gas-barrier film comprising a gas-barrier film as recited inthe first aspect, wherein a plastic film is laminated on either surfaceof the gas-barrier film.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will next be described in detail.

In the present invention, a metallic-compound-containing layer which isapplied to the surface of a polymer layer may be a layer containing ametallic compound alone, or a layer containing a resin in which ametallic compound is mixed or dispersed (hereinafter the layer will bereferred to as “layer of a mixture of metallic compound and resin”). Asused herein, the phrase “a metallic-compound-containing layer is appliedto the surface of a polymer layer” refers to “a metallic compound or asuspension of a mixture of metallic compound and resin is applied orsprayed to the surface of a polymer layer,” “the metallic compound orthe suspension is applied to the surface of a polymer layer throughdipping,” or “powder of the metallic compound is applied to the surfaceof a polymer layer through powdering or spraying.” The phrase does notrefer to application of a metallic-compound-containing layer throughdeposition or sputtering.

The metallic-compound-containing layer of the gas-barrier film of thepresent invention differs in terms of surface roughness from a metalliccompound layer of continuous phase which is produced through depositionor sputtering. The metallic-compound-containing layer may have anon-continuous phase or a continuous phase. In the present invention, ametallic-compound-containing layer can be introduced through aconvenient process as described below, such as powdering of a metalliccompound, or application or spraying of a suspension of the metalliccompound. As described above, a metallic-compound-containing layer whichcontains a heat-resistant resin of high Young's modulus as a plasticfilm and which is produced through deposition or sputtering, whichprocesses require complicated operation and expensive apparatus, has amean surface roughness (Ra) of 0.0002-0.002 μm as measured by use of anatomic force microscope (AFM), or an Ra of 0.0001-0.002 μm as calculatedthrough the below-described method making use of a micrograph oftransmission electron microscope (TEM). In contrast, in the presentinvention, a layer containing a metallic compound alone or a layer of amixture of metallic compound and resin has an Ra of 0.003-0.03 μm asmeasured by AFM, preferably 0.003-0.02 μm, and an Ra of 0.003-5 μm ascalculated by use of a TEM micrograph, more preferably 0.01-3 μm.

In the film of the present invention in which ametallic-compound-containing layer is applied to the surface of apolymer layer formed from a mixture of a poly(meth)acrylic acid polymerand a polyalcohol, a metal invades the polymer layer from themetallic-compound-containing layer. As described below, invasion of ametal can be confirmed by means of energy-dispersive X-ray spectroscopy(EDX). The existence ratio in the polymer layer (the number of countingof metallic atoms/the number of counting of oxygen atoms) is 0.1-20 at aposition 0.1 μm deep in a polymer layer from the interface between thepolymer layer and a layer containing a metallic compound solely or alayer of a mixture of metallic compound and resin, preferably 0.5-10.When the existence ratio is high, the amount of a metallic compound in apolymer layer is large.

The present invention provides a gas-barrier film which is producedthrough application of a metallic-compound-containing layer to thesurface of a polymer layer, the polymer layer being produced throughdrying of a mixture of a polyalcohol and at least one poly(meth)acrylicacid polymer selected from the group consisting of poly(meth)acrylicacids and partially neutralized poly(meth)acrylic acids. The presentinvention also provides a gas-barrier film in which the surface of thepolymer layer to which the metallic-compound-containing layer is notapplied is fixed onto a substrate layer. In the present invention, inorder to impart some degree of water-resistance and gas-barrierproperties to the polymer layer, at least the polymer layer ispreferably subjected to heat treatment. In addition, the polymer layermust be adjacent to a metallic-compound-containing layer or a layer of amixture of metallic compound and resin.

[Poly(meth)acrylic acid polymer]

As used herein, the term “poly(meth)acrylic acid polymer” refers toacrylic acid polymers or methacrylic acid polymers containing two ormore carboxyl groups, and to carboxylic acid polymers or partiallyneutralized carboxylic polymers. Specific examples of poly(meth)acrylicacids include a polyacrylic acid, a polymethacrylic acid, a copolymer ofacrylic acid and methacrylic acid, and a mixture of two or more speciesthereof. In the present invention, a copolymer of acrylic acid ormethacrylic acid, and a methyl ester or ethyl ester thereof may beemployed, so long as the copolymer can be dissolved in a solvent such aswater or alcohol, or in a solvent mixture of water and alcohol. Of theaforementioned examples, a homopolymer of acrylic acid or methacrylicacid, or a copolymer of acrylic acid and methacrylic acid is preferable.In consideration of oxygen-gas-barrier properties, a homopolymer ofacrylic acid or a copolymer of acrylic acid and methacrylic acid inwhich the amount of acrylic acid is greater than that of methacrylicacid is more preferable. The number average molecular weight of apoly(meth)acrylic acid polymer is not particularly limited, but inconsideration of handling, the number average molecular weight ispreferably 1,000-4,000,000, more preferably 2,000-250,000.

Partially neutralized poly(meth)acrylic acid may be produced bypartially neutralizing carboxyl groups of poly(meth)acrylic acid with analkali (i.e., by producing carboxylic acid salts). Examples of alkaliswhich may be employed include alkali metal hydroxides such as sodiumhydroxide, lithium hydroxide, and potassium hydroxide; and ammoniumhydroxide. Partially neutralized poly(meth)acrylic acid is typicallyproduced by adding an alkali to an aqueous solution of poly(meth)acrylicacid for reaction between the alkali and the acid. Partially neutralizedpoly(meth)acrylic acid may be an alkali metal salt or ammonium salt ofthe acid. Such an alkali metal salt or ammonium salt is contained in apolymer layer as a monovalent metal or an ammonium ion. When partiallyneutralized poly(meth)acrylic acid is employed, coloring of a polymerlayer due to heat may be suppressed. Therefore, partially neutralizedpoly(meth)acrylic acid is preferably employed in accordance with needs.

The degree of neutralization of partially neutralized poly(meth)acrylicacid may be desirably determined by regulating the ratio of the amountof poly(meth)acrylic acid to that of an alkali. The degree ofneutralization of partially neutralized poly(meth)acrylic acid ispreferably determined on the basis of oxygen-gas-barrier properties of aproduced film. The degree of neutralization may be obtained by use ofthe following formula: degree of neutralization (%)=(N/N₀)×100. In theformula, N represents the amount by mol of neutralized carboxyl groupsin 1 g of partially neutralized poly(meth)acrylic acid; and Norepresents the amount by mol of carboxyl groups in 1 g ofnon-neutralized poly(meth)acrylic acid.

According to Japanese Patent Application Laid-Open (kokai) No. 7-165942,oxygen-gas-barrier properties of a film produced from at least onepoly(meth)acrylic acid polymer (A) selected from the group consisting ofpoly(meth)acrylic acids and partially neutralized poly(meth)acrylicacids and a polyalcohol polymer (B)—the film being employed in a polymerlayer of the gas-barrier film of the present invention—are affected byheat treatment conditions during formation of the film, or by the degreeof neutralization of the polymer (A) when the mixture ratio of these twopolymers is constant. As compared with the case in whichpoly(meth)acrylic acid is employed as the polymer (A), when neutralizedpoly(meth)acrylic acid is employed, oxygen-gas-barrier properties of aproduced film tend to be enhanced. However, when the degree ofneutralization increases, oxygen-gas-barrier characteristic of theproduced film tend to deteriorate once it has reached a maximal value(i.e., a minimal value of oxygen permeability). When the degree ofneutralization is in excess of 20%, oxygen-gas-barrier properties of aproduced film deteriorate as compared with the case in whichnon-neutralized poly(meth)acrylic acid is employed.

Therefore, from the viewpoint of oxygen-gas-barrier properties,non-neutralized poly(meth)acrylic acid or partially neutralizedpoly(meth)acrylic acid (the degree of neutralization: 20% or less) ispreferably employed as poly(meth)acrylic acid polymer constituting apolymer layer in the gas-barrier film of the present invention. Morepreferably, non-neutralized poly(meth)acrylic acid or partiallyneutralized poly(meth)acrylic acid (degree of neutralization: 15% orless) is employed. Much more preferably, partially neutralizedpoly(meth)acrylic acid (degree of neutralization: 1-13%) is employed.

[Polyalcohol]

As used herein, the term “polyalcohol” refers to low molecular weightcompounds containing two or more hydroxyl groups, alcohol polymers,polyvinyl alcohols (PVA), sugars, and starches. Examples of lowmolecular weight compounds containing two or more hydroxyl groupsinclude glycerin, ethylene glycol, propylene glycol, 1,3-propanediol,pentaerythritol, polyethylene glycol, and polypropylene glycol. PVAwhich may be employed has a saponification percentage of 95% or more,preferably 98% or more, and has an average degree of polymerization of300-1,500. In consideration of compatibility with poly(meth)acrylic acidpolymer, a vinyl alcohol-poly(meth)acrylic acid copolymer predominantlycontaining vinyl alcohol may be employed. Sugars which may be employedinclude monosaccharides, oligosaccharides, and polysaccharides. Suchsugars also include sugar alcohols such as sorbitol, mannitol, dulcitol,xylitol, erythritol, and a variety of substitution compounds andderivatives thereof, which are disclosed in Japanese Patent ApplicationLaid-Open (kokai) No. 7-165942. Such sugars preferably have solubilityin water, alcohol, or a solvent mixture of water and alcohol.

Starches are a class of polysaccharides. Example of starches which maybe employed in the present invention include plant starches (unmodifiedstarches) such as wheat starch, corn starch, glutinous corn starch,potato starch, tapioca starch, rice starch, sweet potato starch, andsago starch; and a variety of modified starches. Examples of modifiedstarches include physically modified starches, enzymatically modifiedstarches, chemical-decomposition modified starches, chemically modifiedstarches, and graft starches which are produced throughgraft-polymerization of starches and a monomer. Of these starches,water-soluble modified starch which is produced by, for example,hydrolyzing potato starch with an acid is preferable. Sugar alcoholwhich is produced by substituting an end group (aldehyde group) ofstarch with a hydroxyl group is more preferable. Starches may be in theform of a hydrate. These starches may be employed singly or incombination of two or more species.

In consideration of production of a polymer layer exhibiting excellentoxygen-gas-barrier properties under high humidity, the mixture ratio (byweight) of poly(meth)acrylic acid polymer to polyalcohol is preferably99:1−20:80, more preferably 95:5−40:60, much more preferably 95:5−50:50.

Preparation and formation of the polymer layer which is a constituent ofthe present invention will next be described. A mixture of apoly(meth)acrylic acid polymer and a polyalcohol is prepared through anyof the following methods: a method in which each component is dissolvedin water; a method in which aqueous solutions of the components aremixed with each other; and a method in which an acrylic acid monomer ispolymerized in an aqueous solution of a polyalcohol. When an acrylicacid monomer is polymerized in an aqueous solution of a polyalcohol, ifdesired, the resultant poly(meth)acrylic acid is neutralized with analkali. When poly(meth)acrylic acid and, for example, sugar aredissolved in water, an aqueous solution of uniform mixture is obtained.Instead of water, a solvent such as alcohol, or a solvent mixture ofwater and alcohol may be employed.

When a polymer layer is subjected to heat treatment for imparting waterresistance and further enhanced gas-barrier properties to the product,in order to moderate the conditions of the treatment, a water-solublemetallic salt of inorganic or organic acid may appropriately be added toan aqueous solution of a mixture of the above polymers duringpreparation of the solution. A metal of the salt may be an alkali metalsuch as lithium, sodium, or potassium. Specific examples of metallicsalts of inorganic or organic acid include lithium chloride, sodiumchloride, potassium chloride, sodium bromide, sodium phosphite (sodiumhypophosphite), disodium hydrogenphosphite, disodium phosphate, sodiumascorbate, sodium acetate, sodium benzoate, and sodium hyposulfite. Aphosphine acid metallic salt (hypophosphorous acid metallic salt) whichis at least one species selected from among phosphine acid metallicsalts (hypophosphorous acid metallic salts) such as sodium phosphite(sodium hypophosphite) and calcium phosphite (calcium hypophosphite) ispreferable. The amount of a metallic salt of inorganic or organic acidwhich is added is preferably 0.1-40 parts by weight on the basis of thesolid content of a solution of a mixture of the polymers, morepreferably 1-30 parts by weight.

The process for forming a polymer layer from the above-preparedcomposition is not particularly limited. For example, a polymer layer isobtained through any of the following processes: a solution-cast processin which an aqueous solution of a polymer mixture is applied onto asupport (substrate) and dried to form a film; an extrusion process inwhich an aqueous solution containing a polymer mixture at highconcentration is cast through a tiny space by use of an extruder underejection pressure, and the resultant water-containing film is dried on arotary drum or belt; and a process in which an aqueous solutioncontaining a polymer mixture at high concentration is applied onto aplastic film, and the film is stretched under heating. Alternatively,when a substrate has a complicated shape, the substrate may be dipped ina solution of a raw material composition, to thereby coat the surface ofthe substrate with the resultant film. A dried film which is produced asdescribed above will be referred to as “a polymer layer.” of theaforementioned processes, a solution-cast process (cast process orcoating process) is preferably employed, since a polymer layer (driedfilm) of excellent transparency can be easily produced.

When a polymer layer is produced through a solution-cast process, thesolid content of a solution of the polymer mixture is preferably 1-30wt. %. When an aqueous solution of a polymer mixture is prepared, ifnecessary, a solvent other than water, such as alcohol, or a softeningagent may appropriately be added to the solution. Alternatively, aplasticizer (excluding a low molecular weight compound containing two ormore hydroxyl groups), a heat stabilizer, or an inorganiclamella-structured compound such as smectic ore may be incorporated inadvance into at least one of poly(meth)acrylic acid polymer andpolyalcohol. The thickness of the polymer layer is appropriatelydetermined in accordance with the purpose of use of a final product. Thethickness is not particularly limited, but is preferably 0.01-100 μm,more preferably 0.1-50 μm.

In a coating process, for example, a solution of a mixture ofpoly(meth)acrylic acid and sugar is applied onto a support (substrate)such as a metallic plate, a glass plate, or a plastic plate so as toattain a desired thickness, by use of an apparatus such as an air knifecoater, a kiss roll coater, a metaling bar coater, a gravure rollcoater, a reverse roll coater, a dip coater, or a die coater, or by useof a combination thereof. Subsequently, the thus-applied solution isdried by evaporating water through spraying of hot air or radiation ofIR rays by use of an apparatus such as an arch drier, a straight bathdrier, a tower drier, a floating drier, or a drum drier, or by use of acombination thereof, to thereby form a film (processed-polymer layer).

Subsequently, a layer constituted solely by a metallic compound or alayer of a mixture of metallic compound and resin, serving as ametallic-compound-containing layer, is applied to the surface of apolymer layer which is fixed onto a substrate. Preferred examples ofmetals constituting a metallic compound include alkali metals such aslithium, sodium, calcium, rubidium, and cesium; alkaline earth metalssuch as beryllium, magnesium, calcium, strontium, and barium; andtransition metals having an oxidation number of +2 such as zinc.Examples of metallic compounds which may be employed include metallicelements; inorganic salts such as oxides, hydroxides, halides, andcarbonates; organic salts such as carboxylates and sulfonates; andpolyacid salts such as poly(meth)acrylates. Of these, oxides,hydroxides, or carbonates of alkaline earth metal or transition metalhaving an oxidation number of +2 are preferable. More preferably, inconsideration of handling and adhesion to a polymer layer, there isemployed at least one metallic compound which is selected from amongmagnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide,zinc oxide, zinc hydroxide, magnesium carbonate, and calcium carbonate.A metallic compound preferably has the form of particles.

The method for application of a metallic-compound-containing layer isnot particularly limited, so long as the layer is adjacent to a polymerlayer. In the case of application of a layer containing a metalliccompound alone, the layer is applied to a polymer layer through, forexample, any of the following processes: a process in which a metalliccompound is powdered; a process in which a metallic compound isdispersed in a solvent and then the resultant suspension is applied ontoa polymer layer by use of a gravure roll coater, a reverse roll coater,a dip coater, or a die coater; and a process in which such a suspensionis sprayed to a polymer layer. In the present invention, thethus-applied metallic compound particle layer may have a continuousphase or non-continuous phase.

The solvent for preparing a suspension of metallic compound is notparticularly limited, and water, any of a variety of solvents, orsolvent mixtures may be employed. In consideration of dispersibility ofmetallic compound particles, applicability of a suspension of metalliccompound, or handling of the suspension, a solvent is arbitrarily chosenfrom among alcohols, aliphatic hydrocarbons, and aromatic compounds. Thesolvent is preferably an alcohol having a carbon number of 10 or less.When a layer constituted solely by a metallic compound is employed, thelayer is not necessarily applied to the entire surface of a polymerlayer as a deposition film is required to do so. The amount of themetallic compound that is applied to the polymer layer is preferably0.01-20 g/m², more preferably 0.03-10 g/m², much more preferably 0.06-5g/m². When the amount is in excess of the upper limit of the aboverange, application cannot be carried out, due to splashing of a metalliccompound, whereas when the amount is below the lower limit of the aboverange, a produced film exhibits insufficient gas-barrier properties.

In the case of application of a layer of a mixture of metallic compoundand resin, the layer contains at least one resin which is selected fromamong an alkyd resin, a melamine resin, an acrylic resin, a urethaneresin, nitrocellulose, an epoxy resin, a polyester resin, a phenolresin, an amino resin, a fluorine-containing resin, and isocyanate. Theweight ratio of a metallic compound to a resin (i.e., metalliccompound/resin) is preferably 0.01-1,000, more preferably 0.01-100. Amixture of a metallic compound and a resin may be dissolved or dispersedin an organic solvent to prepare a dispersion or a suspension, afterwhich the resultant dispersion or suspension is applied or sprayed to apolymer layer. The case in which a mixture of a metallic compound and aresin is employed is more preferable than the case in which a metalliccompound is employed alone, since a metallic compound is uniformlyapplied to a polymer layer when the mixture is employed. In order toprepare a dispersion or a suspension, there may be employed any of thesolvents which may be employed in the case in which a metallic compoundis solely applied. When a mixture of metallic compound and resin isapplied, the amount of the mixture which is applied to a polymer layermay be determined by regulating the amount of a metallic compound beingpreferably 0.03-20 g/m², more preferably 0.06-10 g/m², much morepreferably 0.06-5 g/m².

When a metallic compound is applied through deposition or sputtering,the resultant metallic-compound-applied surface may have a mean surfaceroughness (Ra) of less than 0.003 μm as measured by AFM or as calculatedby use of a TEM micrograph. However, such an application process isdisadvantageous, in that a resin employed must have heat resistance andhigh Young's modulus, and that operation is cumbersome and an expensiveapparatus is required, since deposition or sputtering must be carriedout in a vacuum apparatus. When the Ra of a metallic-compound-containinglayer is in excess of 0.03 μm as measured by AFM or is in excess of 5 μmas calculated by use of a TEM micrograph, adhesion between themetallic-compound-containing layer and a polymer layer is poor, which isnot practical. Incidentally, metallic atoms are present in a polymerlayer of the gas-carrier film of the present invention in which ametallic-compound-containing layer is applied to the polymer layerproduced from a mixture of a poly(meth)acrylic acid polymer and apolyalcohol; or metallic atoms are present in a polymer layer of alaminated gas-barrier film comprising the gas-barrier film and a plasticfilm laminated thereon. As described below, invasion of a metal into apolymer layer can be confirmed by means of EDX, and the existence ratioin the polymer layer (number of counting of metallic atoms/number ofcounting of oxygen atoms) is 0.1-20, preferably 0.5-10, at a position0.1 μm deep in a polymer layer from the interface between the polymerlayer and a layer constituted by a metallic compound alone or a layer ofa mixture of metallic compound and resin. When the degree is less than0.1, the polymer layer exhibits insufficient gas-barrier properties,whereas the ratio is in excess of 20, a polymer layer may break, andthus exhibits insufficient gas-barrier properties.

In order to enhance water resistance and gas-barrier properties of apolymer layer which is fixed onto a substrate, at least the polymerlayer may be subjected to heat treatment. A polymer layer to which ametallic compound is applied may be subjected to heat treatment underspecific conditions, or a metallic compound may be applied to thesurface of a polymer layer after the polymer layer is subjected to heattreatment.

As used herein, the term “a polymer layer which is fixed onto asubstrate” refers to “a polymer layer, to which ametallic-compound-containing layer is not applied, which is fixed onto asubstrate” or “a polymer layer which may be peeled off a substrate.” Thematerial of a substrate is not particularly limited, and a metallicplate, a glass plate, or a plastic film may be employed as a substrate.Of these, a plastic film is preferably employed. More preferably, asubstrate is chosen from a variety of plastic films in accordance withheat treatment temperature or the intended use of a gas-barrier film(for example, a gas-barrier film is used in sterilization treatment).Examples of materials of plastic film include polyester resins such aspolyethylene terephthalate (PET), polybutylene terephthalate (PBT), andpolyethylene naphthalate (PEN); polyamides such as nylon 6, nylon 66,nylon 12, a nylon 6′66 copolymer, a nylon 6′12 copolymer, amethaxylylenadipamide nylon 6 copolymer, and amorphous nylon;polyolefins such as low density polyethylene, high density polyethylene,linear low density polyethylene, an ethylene.vinyl acetate copolymer,polypropylene, an ethylene.acrylic acid copolymer, an ethylene.acrylatecopolymer, an ethylene.ethyl acrylate copolymer, andpoly(methylpentene); polyvinylidene chloride; and polyphenylene sulfide.In order to enhance adhesion between a polymer layer and a substratelayer, an anchoring agent may be applied to the substrate layer.

A polymer layer is subjected to heat treatment under the conditionsdisclosed in Japanese Patent Application Laid-Open (kokai) No. 8-41218.Specifically, when a sugar is employed as a polyalcohol, a polymer layeris preferably subjected to heat treatment under conditions satisfyingthe relations between heat treatment temperature and heat treatment timeas specified by the following formulas (a) and (b):

(a) log t≧.0.0253×T+11.2

(b) 373≦T≦573

[wherein t represents heat treatment time (minutes), and T representsheat treatment temperature (K)].

When a polymer layer is subjected to heat treatment under the aboveconditions, the resultant layer has water resistance. In addition, therecan be produced a polymer film exhibiting excellent gas-barrierproperties; i.e., a polymer layer having a thickness of 2 μm has anoxygen permeability of 2.0×10⁻¹² mol/m²·s·Pa (400 cm³/m²·24h·atm) orless as measured at 30° C. and 80% RH.

A polymer layer, such as a polymer film, a laminate comprising asubstrate and a film, or a polymer layer to which ametallic-compound-containing layer is applied, may be subjected to heattreatment by placing the layer in an oven, which is then heated at apredetermined temperature for a predetermined time. Alternatively, apolymer layer may be continuously subjected to heat treatment by passingthe layer through an oven which is heated at a predetermined temperaturewithin a predetermined time, or by bringing the layer into contact witha heat roll. After completion of heat treatment, the resultant polymerlayer has water resistance and exhibits excellent gas-barrier propertiesunder high humidity. In addition, the resultant polymer layer isinsoluble in water or boiling water, and has water resistance asspecified as follows. As used herein, the phrase “a polymer layer haswater resistance” refers to the case in which, when a film comprising apolymer layer is dipped in boiling water for 30 minutes and then dried,the thickness of the polymer layer is 50% or more that of the polymerlayer before being dipped in boiling water.

In order to impart strength or sealability to the gas-barrier film ofthe present invention, a plastic film may further be laminated on thegas-barrier film, to thereby form a laminated gas-barrier film. The typeof a laminated gas-barrier film is not particularly limited. Specificexamples of layer structures of laminated gas-barrier film includepaper/polyethylene terephthalate layer/polymer layer/metallic compoundlayer/non-stretched polypropylene layer; polyethylene terephthalatelayer/polymer layer/metallic compound layer/non-stretched polypropylenelayer; polyethylene terephthalate layer/polymer layer/metallic compoundlayer/linear low density polyethylene layer; polyethylene terephthalatelayer/polymer layer/metallic compound layer/low density polyethylenelayer; polyethylene terephthalate layer/polymer layer/metallic compoundlayer/ethylenic copolymer produced by use of a metallocene catalyst;polyethylene terephthalate layer/polymer layer/metallic compoundlayer/propylenic copolymer produced by use of a metallocene catalyst;stretched nylon layer/polymer layer/metallic compoundlayer/non-stretched polypropylene layer; stretched nylon layer/polymerlayer/metallic compound layer/linear low density polyethylene layer;stretched nylon layer/polymer layer/metallic compound layer/low densitypolyethylene layer; stretched nylon layer/polymer layer/metalliccompound layer/ethylenic copolymer produced by use of a metallocenecatalyst; and stretched nylon layer/polymer layer/metallic compoundlayer/propylenic copolymer produced by use of a metallocene catalyst.The aforementioned metallic compound layer may be a layer containing ametallic compound alone or a layer of a mixture of metallic compound andresin.

In order to produce the aforementioned laminated film, a plastic filmlayer formed of a thermoplastic resin may be laminated on either or bothof the surface of a substrate and the surface of ametallic-compound-containing layer, with or without intervention of anadhesive layer, by means of a known lamination method such as coating,dry lamination, or extrusion coating. In dry lamination, a plastic filmor sheet formed of a thermoplastic resin is laminated on ametallic-compound-containing layer or on a second surface of a substrateof a gas-barrier film, the gas-barrier film comprising a polymer layerwhich is fixed onto a first surface of the substrate, and ametallic-compound-containing layer which is applied onto the polymerlayer. In extrusion coating, a thermoplastic resin is melt-extruded on asubstrate layer or on a metallic compound layer which is applied onto apolymer layer, and a plastic film is laminated thereon, to therebyproduce a laminated film.

One of the outer layers of a laminated gas-barrier film is preferablyproduced from a material which enables heat sealing, high-frequencysealing, or ultrasonic sealing, (i.e., sealant), in consideration ofheat adhesion of the films when a bag is produced from the films.Examples of resins which enable heat sealing include polyolefins such aslow density polyethylene, linear low density polyethylene, high densitypolyethylene, an ethylene.vinyl acetate copolymer, an ethyleniccopolymer produced by use of a metallocene catalyst, a propyleniccopolymer produced by use of a metallocene catalyst, non-stretchedpolypropylene, an ethylene.acrylic acid copolymer, an ethylene.acrylicacid salt copolymer, and an ethylene.ethyl acrylate copolymer; and nyloncopolymers such as a nylon 6′66 copolymer and a nylon 6′12 copolymer.Examples of resins which enable high-frequency sealing include polyvinylchloride, polyvinylidene chloride, nylon 6, and nylon 66. Examples oftypes of sealing include four-corner sealing, three-corner sealing, buttsealing, and envelope sealing.

The gas-barrier film of the present invention and the laminatedgas-barrier film produced therefrom exhibit excellent oxygen-gas-barrierproperties in an atmosphere of high humidity. Therefore, the films aresuitably employed for packaging material of beverages or foodssusceptible to oxygen, such as furikake (processed seasoning granules),wine, dried bonito, miso, ketchup, and snacks. Particularly, the filmsare suitably employed for packaging material of foods which undergosterilization treatment such as retorting or boiling, such as curry,stew, broth, sauce, and corn. The films are employed in the form of, forexample, bag, casing, pouch, or capping material.

EXAMPLES

The present invention will next be described in more detail by way ofExamples, which should not be construed as limiting the inventionthereto.

[Oxygen Permeability]

Oxygen permeability was measured by use of an oxygen permeabilitymeasuring instrument (™OX-TRAN2/20, product of Modern Control) at 30° C.and 80% RH. Oxygen permeability of a polymer layer (containing ametallic compound layer) was determined by the following equation:

1/P _(total)=1/P _(sample)+1/P _(base)

wherein “P_(total)” represents a measured value, “P_(base)” representsoxygen permeability of a substrate film, and “P_(sample)” representsoxygen permeability of a polymer layer (including a layer containing ametallic compound).

[Water Resistance]

A sample film of 10 cm×10 cm, containing a substrate and a polymer layerfixed thereto, was immersed in boiling water for 30 minutes. Thicknessof the polymer layer was measured before and after the immersionprocedure, and water resistance of the sample was estimated as follows.

When the sample satisfies the relation represented by the followingformula:

(Ta−Tb)/(Ta−Tc)≦0.5,

the sample is estimated as water-resistant and rating “O” is assigned.In contrast, when the relation is not satisfied the sample is estimatedas non-water-resistant and rating “X” is assigned. In above-describedformula, “Ta” (unit: μm) represents the thickness of the sample filmbefore immersion, “Tb” (unit: μm) represents the thickness of the samplefilm after immersion followed by drying treatment, and “Tc” (unit: μm)represents the thickness of a substrate.

[Mean Surface Roughness (Ra)]

There are two methods for measuring mean surface roughness. A suitablemethod was employed according to the form of each sample to be measured.When it was possible to expose a surface of metallic compound layer or asurface of layer of a mixture of metallic compound and resin (Examples1-18 and Comparative Examples 1-10), Ra value was measured by use of anAFM. When it was possible to observe the cross section of a sample as inthe case of a laminate, Ra value was measured by use of a TEM. In thelatter case, two Ra values were obtained with respect to each sample.One is an Ra value obtained through observation of a cross section of alayer containing a metallic-compound-containing layer applied on apolymer layer, and the other is an Ra value obtained through observationof a cross section of a substrate layer. The higher Ra value thereof wasregarded as mean surface roughness.

With respect to Examples 1-18 and Comparative Examples 1-10, the resultsof AFM measurement are shown in Tables. With respect to Examples 19-58,the results of AFM measurement and TEM measurement are shown in Tables.

Ra value obtained through AFM measurement is mean surface roughness of ametallic compound layer or a layer of a mixture of metallic compound andresin.

Surface roughness of a vapor-deposited layer, a metallic compound layer,or a layer of a mixture of metal compound and resin was measured by useof an AFM (atomic force microscope) of a scanning probe microscope(SP13800D series; product of Seiko Instruments Inc.). The microscope wasoperated in cyclic contact mode. An area of 2 μm×2 μm was observed at amagnification of 40,000. From the thus-obtained images, ten areas wererandomly sampled and Ra (μm) values thereof were averaged.

Ra value obtained thorough TEM measurement is mean surface roughness,which is obtained through observation of a cross section of a laminate.

A laminate film was embedded in epoxy resin and the sample was sliced byuse of a cryomicrotome so as obtain an ultra-thin sliced piece. Thethus-obtained sliced piece was observed under a TEM at a magnificationof 1,400,000 for a vapor-deposited layer and at 40,000 for a metalliccompound layer or a layer of a mixture of metallic compound and resin.Each sample was observed before retort treatment.

According to JIS B0601, Ra (μm) of each sample was calculated by use ofthe thus-obtained images and the following equation:

Ra=1/l∫ ₀ ^(l) |f(x)|dx

(l: standard length, ∫₀ ^(l): integral (0 to l)).

The mean line was set at the midpoint of the highest peak and the lowestvalley. Observed range with respect to a vapor-deposited layer was 0.06μm. Observed range with respect to a metallic compound layer or a layerof a mixture of metallic compound and resin was 2.5 μm.

[Existence Ratio of Metallic Compound in a Polymer Layer]

Existence ratio was measured by use of TEM-EDX.

An ultra-thin sliced piece of each sample was irradiated with anelectron beam. The species of element and the amount thereof wasdetermined by wavelength of X-rays generated from the piece, to therebyobtain the amount of a metallic atom in a depth direction of a polymerlayer. A sample before retort treatment was employed.

Apparatus employed and measuring conditions are as follows.

TEX: Transmission electron microscope (model: HF-2000, product ofHitachi Ltd.)

EDX: Energy-dispersive X-ray spectroscopy (model: VOYAGER III M3100,product of NORAN)

X-ray detector: Si/Li semiconductor detector

Beam size: about 100 mmφ

Measuring time: 50 seconds

Existence ratio of a metal compound was obtained by dividing the numberof counting of metallic atoms contained in a polymer layer by the numberof counting of oxygen atoms.

Examples 1-3

A 25 wt. % aqueous solution of polyacrylic acid (PAA; product ofToagosei Co., Ltd.; viscosity at 30° C.=8,000−12,000 cps; number-averagemolecular weight=150,000) was diluted with distilled water to prepare a15 wt. % aqueous solution. Subsequently, to the thus-prepared PAAaqueous solution, calculated amount of the sodium hydroxide with respectto the number of moles of carboxyl groups of the PAA was added tothereby obtain a partially neutralized PAA aqueous solution having adegree of neutralization of 5%. Subsequently, sodium phosphinatemonohydrate (product of Wako Pure Chemical Industries, Ltd.; specialtygrade) was added to the partially neutralized PAA aqueous solution so asto obtain a partially neutralized PAA aqueous solution containing sodiumphosphinate, wherein the amount of the sodium phosphinate monohydrateadded to the partially neutralized PAA aqueous solution was two parts byweight with respect to 100 parts by weight of the solid content of thePAA aqueous solution.

Separately, a 15 wt % aqueous solution of soluble starch (product ofWako Pure Chemical Industries, Ltd.; first grade; hydrolysis product ofpotato starch with acid) was prepared. The thus-obtained starch aqueoussolution and the above-described partially neutralized PAA aqueoussolution containing sodium phosphinate were mixed together at variousweight ratios, to thereby obtain aqueous solution mixtures(concentration: 15 wt %).

By use of a Mayer bar and a tabletop coater (K303 PROOFER; product of RKPrint-Coat Instruments), the thus-obtained aqueous solution was appliedonto stretched polyethylene terephthalate film (PET; Lumirror S10;product of Toray Industries, Inc.; thickness−12 μm) serving as asubstrate material. Subsequently, moisture was evaporated by use of adryer to thereby obtain a dry film having a thickness of 2 μm.

Magnesium oxide particles (MgO; product of Wako Pure ChemicalIndustries, Ltd.) having a diameter of 0.01 μm were suspended in ethylalcohol(product of Wako Pure Chemical Industries, Ltd.; specialty grade)so as to obtain a MgO/ethyl alcohol suspension having a concentration of57 g/l. The dry film described above was coated with the thus-obtainedsuspension in a manner similar to the above-described coating procedure.Subsequently, the stretched PET film bearing the MgO-coated dried filmthereon was secured onto cardboard by use of adhesive tape. Thethus-obtained sample was heated in a 180° C. oven for 15 minutes. Theheat-treated film including an MgO-coated dried film exhibited waterresistance as specified in the present invention. Each of thethus-obtained water-resistant films (thickness of the film=2.5 μm,thickness of the deposited MgO layer=0.5 μm) was evaluated for waterresistance and oxygen permeability. Table 1 shows water resistance,oxygen permeability, coating conditions of metal compound, andheat-treatment conditions with respect to the above-described Examples,other Examples that follow, and Comparative Examples.

Example 4

The procedure described in Example 1 was repeated to thereby obtain awater-resistant film, except that polyvinyl alcohol (PVA) (Poval 105;product of Kuraray Co., Ltd.; degree of polymerization=500;saponification degree ≧98%) was used instead of the soluble starchemployed in Examples 1-3 and that the partially neutralized PAA aqueoussolution containing sodium phosphinate and the PVA aqueous solution weremixed together at a weight ratio of 70:30, so as to obtain a 15 wt. %solution.

Example 5

The procedure described in Example 1 was repeated to thereby obtain awater-resistant film, except that sugar alcohol (PO20; product of TowaChemical Industry. Co., Ltd.) was used instead of the soluble starchemployed in Examples 1-3 and that the partially neutralized PAA aqueoussolution containing sodium phosphinate and the sugar alcohol aqueoussolution were mixed together at a weight ratio of 70:30, so as to obtaina 15 wt. % solution.

Examples 6-9

The procedure described in Example 5 was repeated to thereby obtainwater-resistant films, except that the following solvents were used forthe preparation of MgO suspension: n-butyl alcohol (product of Wako PureChemical Industries, Ltd.; specialty grade; Example 6) as an alcohol;acetic acid (product of Wako Pure Chemical Industries, Ltd.; specialtygrade; Example 7) as a carboxylic acid; ethyl acetate (product of WakoPure Chemical Industries, Ltd.; first grade; Example 8) as an ester; andtoluene (product of Wako Pure Chemical Industries, Ltd.; first grade;Example 9) as an aromatic compound.

Examples 10 and 11

The procedure described in Example 2 was repeated to thereby obtainwater-resistant films, except that calcium hydroxide (Example 10) orzinc oxide (Example 11) was used instead of the magnesium oxide.

Examples 12 and 13

The procedure described in Example 2 was repeated to thereby obtainwater-resistant films, except that stretched nylon film (O-Ny; productof Unitika Ltd.; thickness=15 μm; Example 12) or non-orientedpolypropylene film (CPP) (Torayfan ZK93K; product of Toray Plastic FilmsCo., Ltd.; thickness=70 μm; Example 13) was used as a substrate materialand that the heat-treatment period was changed shown in Table 1.

Examples 14-18

The procedure described in Example 1 was repeated, except that theconditions shown in Table 1 were employed, to thereby obtainwater-resistant films. Briefly, an MgO/ethyl alcohol suspension having aconcentration of 27 g/l was sprayed onto a layered product by use of agardener's sprayer (Example 14); a dried film was heat-treated, followedby application of an MgO/ethyl alcohol suspension thereto by use of aMayer bar (Example 15); a dried film was heat treated, followed byapplication of an Mgo/water suspension thereto by use of a Mayer bar(Example 16); powdered MgO was sprayed directly onto a layered productby use of a sprayer (Nikka spray K-III; product of Nikka Ltd.) (Example17); or a water-resistant film prepared in accordance with the proceduredescribed in Example 1 was rinsed with water for 20 seconds (Example18).

Comparative Examples 1-10

The procedure described in Examples 1-3 was repeated, except that theconditions shown in Table 1 were employed, to thereby obtain films. Thethus-prepared films were evaluated for water resistance, oxygenpermeability, and mean surface roughness (Ra), which are shown in Table1.

TABLE 1-1 Material of polymer Heat Conditions for application Heat layertreatment of powder treatment Post- Water Oxygen Sub- Mixingratio^((*1)) Temp./Time Amount Temp./Time treat- resis- permea- strate(by weight) ° C. · min. Method Type Solvent g/m² ° C. · min. ment tancebility^((*2)) Ex. 1 PET 80/20 — — Mayer MgO EtOH 0.06 180 15 — ∘ 0.30.009 bar Ex. 2 ″ 70/30 — — Mayer ″ ″ ″ 160 30 — ∘ 0.4 0.009 bar Ex. 3 ″60/40 — — Mayer ″ ″ ″ 180 15 — ∘ 0.6 0.009 bar Ex. 4 ″ 70/30 — — Mayer ″″ ″ ″ ″ — ∘ 0.8 0.009 bar Ex. 5 ″ 70/30 — — Mayer ″ ″ ″ ″ ″ — ∘ 0.40.009 bar Ex. 6 ″ 70/30 — — Mayer ″ nBtOH ″ ″ ″ — ∘ 0.4 0.009 bar Ex. 7″ ″ — — Mayer ″ Acetic ″ ″ ″ — ∘ 0.4 0.009 bar acid Ex. 8 ″ ″ — — Mayer″ Ethyl ″ ″ ″ — ∘ 0.4 0.009 bar acetate Ex. 9 ″ ″ — — Mayer ″ Toluene ″″ ″ — ∘ 0.4 0.009 bar Ex. 10 ″ ″ — — Mayer Ca(OH)₂ EtOH ″ ″ ″ — ∘ 1.00.015 bar Ex. 11 ″ ″ — — Mayer ZnO ″ ″ ″ ″ — ∘ 1.5 0.015 bar Ex. 12 O-Ny″ — — Mayer MgO ″ ″ 160 120  — ∘ 0.8 0.009 bar Ex. 13 CPP ″ — — Mayer ″″ ″ ″ ″ — ∘ 0.8 0.009 bar Ex. 14 PET ″ — — Spray ″ ″ 0.20 180 15 — ∘ 0.40.013 Ex. 15 ″ ″ 180 15 Mayer ″ ″ 0.06 ″ ″ — ∘ 0.3 0.009 bar Ex. 16 ″ ″180 15 Mayer ″ Water ″ — — — ∘ 0.4 0.009 bar Ex. 17 ″ ″ — — Powder- ″ —0.20 180 15 — ∘ 0.6 0.012 ing Ex. 18 ″ ″ — — Mayer ″ EtOH 0.06 ″ ″ Wash-∘ 0.4 0.005 bar ing ^((*1))polyacrylic acid/polyalcohol ^((*2))Unit(cm³/m² · 24 h · atm), 30° C., 80% RH

TABLE 1-2 Material of polymer Heat Conditions for application Heat layertreatment of powder treatment Post- Water Oxygen Sub- Mixingratio^((*1)) Temp./Time Amount Temp./Time treat- resis- permea- strate(by weight) ° C. · min. Method Type Solvent g/m² ° C. · min. ment tancebility^((*2)) Comp. PET 80/20 — — — — — — 180 15 — ∘ 11.0  0.0004 Ex. 1Comp. ″ 70/30 — — — — — — ″ ″ — ∘ 6.0 0.0004 Ex. 2 Comp. ″ 60/40 — — — —— — ″ ″ — ∘ 5.0 0.0004 Ex. 3 Comp. ″ 70/30 — — — — — — 160 30 — ∘ 8.00.0004 Ex. 4 Comp. ″ 70/30 — — — — — — 180 15 — ∘ 6.0 0.0004 Ex. 5 Comp.″ 70/30 — — Mayer TiO₂ EtOH 0.06 ″ ″ — ∘ 6.0 0.02  Ex. 6 bar Comp. ″70/30 — — Mayer Al(OH)₃ ″ ″ ″ ″ — ∘ 5.0 0.02  Ex. 7 bar Comp. O-Ny ″ — —— — — — 180 15 — ∘ 380 0.0004 Ex. 8 Comp. CPP ″ — — — — — — 180 15 — ∘380 0.0004 Ex. 9 Comp. EVOH 80/20 — — Mayer MgO EtOH 0.06 180 15 — ∘ 6.00.009  Ex. 10 bar ^((*1))polyacrylic acid/polyalcohol ^((*2))Unit(cm³/m² · 24 h · atm), 30° C., 80% RH

Concerning Examples 19-58, procedures are basically the same as thatdescribed in Examples 1-18 except that the following conditions wereemployed. An adhesive agent (TM-590; product of Toyo Morton Ltd.) and acuring agent (CAT-56A; product of Toyo Morton Ltd.) were applied ontothe MgO side of a MgO-coated film. The thickness of the adhesive agentwas 3 μm. Subsequently, a non-oriented polypropylene film (CPP)(Torayfan ZK93K; product of Toray Plastic Films Co., Ltd.; thickness=70μm) was attached to the side to which an adhesive agent and a curingagent had been applied. The thus-obtained layered film wasdry-laminated. Each of the thus-obtained films was treated in waterunder high pressure and heat by use of an autoclave (BS-325; product ofTomy Kogyo Co., Ltd.) at 120° C. for 20 minutes.

Example 19

The procedure described in Example 1 was repeated, except that thefollowing conditions were employed. PO20 (product of Towa ChemicalIndustry. Co., Ltd.) was used instead of the soluble starch used inExample 1; the partially neutralized PAA aqueous solution containingsodium phosphinate and the PO20 aqueous solution were mixed together ata weight ratio of 90:10 instead of 80:20; and a sample was heat-treatedby hot air at 230° C. for 30 seconds instead of being heat-treated in ageared oven at 180° C. for 15 minutes. The thus-obtained film wastreated under high pressure and heat at 120° C. for 20 minutes.

Example 20

The procedure described in Example 19 was repeated, except that thepartially neutralized PAA aqueous solution containing sodium phosphinateand the PO20 aqueous solution were mixed together at a weight ratio of80:20 instead of 90:10.

Example 21

The procedure described in Example 19 was repeated, except that thepartially neutralized PAA aqueous solution containing sodium phosphinateand the PO20 aqueous solution were mixed together at a weight ratio of70:30 instead of 90:10.

Example 22

The procedure described in Example 19 was repeated, except that thepartially neutralized PAA aqueous solution containing sodium phosphinateand the PO20 aqueous solution were mixed together at a weight ratio of60:40 instead of 90:10.

Example 23

The procedure described in Example 21 was repeated, except that thepolyvinyl alcohol (PVA) used in Example 4 was used instead of PO20.

Example 24

The procedure described in Example 20 was repeated, except that asoluble starch (product of Wako Pure Chemical Industries, Ltd.; firstgrade) as polyalcohol was used instead of PO20.

Example 25

The procedure described in Example 20 was repeated, except that sorbitol(product of Wako Pure Chemical Industries, Ltd.) as polyalcohol was usedinstead of PO20.

Example 26

The procedure described in Example 22 was repeated, except that glycerin(product of Wako Pure Chemical Industries, Ltd.; first grade) aspolyalcohol was used instead of PO20.

Example 27

The procedure described in Example 20 was repeated, except that theheat-treatment was performed after dried film prepared from PO20 and thepartially neutralized PAA containing sodium phosphinate was coated withthe MgO suspension in ethyl alcohol, instead of the heat-treatment beingperformed before MgO-coating procedure.

Example 28

The procedure described in Example 21 was repeated, except that theheat-treatment was performed at 160° C. for 15 minutes in a geared oven.

Example 29

The procedure described in Example 26 was repeated, except that theheat-treatment was performed at 160° C. for 15 minutes in a geared oven.

Example 30

The procedure described in Example 20 was repeated, except thatmagnesium hydroxide, Mg(OH)₂, (product of Wako Pure Chemical Industries,Ltd.) was used instead of MgO.

Example 31

The procedure described in Example 20 was repeated, except that calciumhydroxide, Ca(OH) ₂, (product of Wako Pure Chemical Industries, Ltd.)was used instead of MgO.

Example 32

The procedure described in Example 20 was repeated, except that zincoxide, ZnO, having a particle size of 0.02 μm (product of Wako PureChemical Industries, Ltd.) was used instead of MgO.

Example 33

The procedure described in Example 20 was repeated, except that thefollowing conditions were employed. The mixture of the aqueous solutionof partially neutralized PAA containing sodium phosphinate and the PO20aqueous solution was applied to a biaxially stretched nylon film (nylon6; product of Unitika Ltd.; Emblem; thickness=15 μm) instead of the PETfilm, and heat-treatment was performed by use of hot air at 180° C. for30 seconds.

Example 34

The procedure described in Example 20 was repeated, except that theaqueous solution of partially neutralized PAA containing sodiumphosphinate and the PO20 aqueous solution was applied so as to obtain apolymer layer having a thickness of 1 μm instead of 2 μm.

Example 35

The procedure described in Example 20 was repeated, except that aMgo/ethyl alcohol suspension having a concentration of 5 g/l was usedinstead of the suspension having a concentration of 57 g/l.

Example 36

The procedure described in Example 20 was repeated, except that a mixedsolution containing MgO and a resin component, instead of the MgO/ethylalcohol suspension, was applied to a polymer layer containing thepartially neutralized PAA containing sodium phosphinate and PO20.

The mixed solution containing MgO and a resin component was prepared asfollows. Polyester resin (AD335AE; product of Toyo Morton Ltd.) as aresin component and isocyanate (CAT-1; product of Toyo Morton Ltd.) as acuring agent were mixed in a ratio of 10:1. Subsequently, thethus-obtained resin mixture was diluted with a mixed solvent of tolueneand ethyl acetate (weight ratio of 1/1) so as to obtain a resin solutionhaving a nonvolatile content of 10 wt. %. Subsequently, thethus-obtained solution was mixed with MgO, which is the same species asused in Example 2, to thereby obtain a solution. The MgO was mixed sothat the weight ratio of MgO/resin was 1/1. The resultant solution wasapplied to a polymer layer so as to have a thickness of 0.2 μm. Thethus-obtained laminated film was conditioned at 40° C. and 80% RH forthree days.

Example 37

The procedure described in Example 36 was repeated, except that theresin solution was mixed with MgO to thereby obtain a solution, in whichthe weight ratio of MgO/resin is 0.5/1 instead of 1/1.

Example 38

The procedure described in Example 36 was repeated, except that thefollowing conditions were employed. Polyester resin (TM-225AE; productof Toyo Morton Ltd.) as a resin component and isocyanate (TM-225B;product of Toyo Morton Ltd.) as a curing agent were used instead of theresin component (AD-335AE; product of Toyo Morton Ltd.) and isocyanate(CAT-10; product of Toyo Morton Ltd.); the polyester resin and thecuring agent were mixed in a ratio of 16:1; and the thus-obtained resinmixture was diluted with ethyl acetate so as to obtain a resin solutionhaving a nonvolatile content of 10 wt. %.

Example 39

The procedure described in Example 38 was repeated, except that theresin solution was mixed with MgO to thereby obtain a solution, in whichthe weight ratio of MgO/resin was 0.5/1 instead of 1/1.

Example 40

The procedure described in Example 36 was repeated, except that thefollowing conditions were employed. Polyvinyl alcohol (PVA) used inExample 4 was employed instead of the PO20 as a polyalcohol component;and the partially neutralized PAA containing sodium phosphinate and thePVA were mixed together at a weight ratio of 70:30.

Example 41

The procedure described in Example 36 was repeated, except that thefollowing conditions were employed. A soluble starch used in Example 1was employed instead of the PO20 as a polyalcohol component; and thepartially neutralized PAA containing sodium phosphinate and the PVA weremixed together at a weight ratio of 80:20.

Example 42

The procedure described in Example 36 was repeated, except that thefollowing conditions were employed. Sorbitol used in Example 25 wasemployed instead of the PO20 as a polyalcohol component; and thepartially neutralized PAA containing sodium phosphinate and the PVA weremixed together at a weight ratio of 80:20.

Example 43

The procedure described in Example 36 was repeated, except that thefollowing conditions were employed. Glycerin used in Example 26 wasemployed instead of the PO20 as a polyalcohol component; and thepartially neutralized PAA containing sodium phosphinate and the glycerinwere mixed together at a weight ratio of 60:40.

Example 44

The procedure described in Example 36 was repeated, except that thefollowing conditions were employed. 100 parts by weight of a transparentUV shielding dispersion (ZR-133; product of Sumitomo Osaka Cement Co.,Ltd.), in which zinc oxide fine particles were dispersed in polyesterresin at a weight ratio of 1.5/1 (metal compound/resin), was mixed with4 parts by weight of a curing agent (DN-980; product of Dainippon Inkand Chemical Inc.); the thus-obtained mixture was diluted with a solventmixture of toluene and methyl ethyl ketone (weight ratio=6/4) so as toobtain a zinc-oxide-containing resin solution having a desirednonvolatile content; the resultant solution was applied to a polymerlayer so as to have a thickness of 0.2 μm.

Example 45

The procedure described in Example 44 was repeated, except that the zincoxide-containing resin solution was applied to a polymer layer so as tohave a thickness of 0.1 μm instead of 0.2 μm.

Example 46

The procedure described in Example 44 was repeated, except that the zincoxide-containing resin solution was applied to a polymer layer so as tohave a thickness of 0.9 μm instead of 0.2 μm.

Example 47

The procedure described in Example 44 was repeated, except that thefollowing conditions were employed. A biaxially stretched nylon filmused in Example 12 was employed instead of the PET film as a substrate;and heat-treatment was performed by use of hot air at 180° C. for 15minutes instead of heat-treatment in a geared oven.

Examples 48-50

The procedure described in Example 44 was repeated, except that thepartially neutralized PAA containing sodium phosphinate and the PO20were mixed together at a weight ratio of 90:10 (Example 48); 70:30(Example 49); and 60:40 (Example 50) instead of 80:20.

Example 51

The procedure described in Example 44 was repeated, except that athickness of the polymer layer formed of a partially neutralized PAAcontaining sodium phosphinate and the PO20 was changed to 1 μm insteadof 2 μm.

Example 52

The procedure described in Example 44 was repeated, except that apolymer layer containing the partially neutralized PAA containing sodiumphosphinate and PO20 was heat-treated in a geared oven at 160° C. for 15minutes.

Example 53

The procedure described in Example 44 was repeated, except that apolymer layer containing the partially neutralized PAA containing sodiumphosphinate and glycerin in a ratio of 60:40 was heat-treated in ageared oven at 160° C. for 15 minutes.

Example 54

The procedure described in Example 36 was repeated, except thatmagnesium hydroxide (product of Wako Pure Chemical Industries, Ltd.) wasused instead of magnesium oxide.

Example 55

The procedure described in Example 36 was repeated, except that calciumhydroxide (product of Wako Pure Chemical Industries, Ltd.) was usedinstead of magnesium oxide.

Example 56

The procedure described in Example 44 was repeated, except that a CPPfilm was laminated to the PET film side to which an adhesive agent hadbeen applied previously, instead of being laminated to the metalcompound side with intervention of an adhesive agent.

Example 57

The procedure described in Example 44 was repeated, except that abiaxially stretched polyethylene terephthalate film (S10; product ofToray Industries, Inc.; thickness=25 μm) instead of a CPP film waslaminated to the metal compound side to which an adhesive agent had beenapplied previously.

Example 58

The procedure described in Example 20 was repeated, except that theresin solution containing polyester resin AD335AE and isocyanate CAT-10as described in Example 36 was applied to a MgO-coated surface.

Comparative Example 11

The procedure described in Example 19 was repeated, except that theMgo/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 12

The procedure described in Example 20 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 13

The procedure described in Example 21 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 14

The procedure described in Example 22 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 15

The procedure described in Example 25 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 16

The procedure described in Example 26 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 17

The procedure described in Example 24 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 18

The procedure described in Example 23 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 19

The procedure described in Example 28 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 20

The procedure described in Example 29 was repeated, except that theMgO/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 21

The procedure described in Example 33 was repeated, except that theMgo/ethyl alcohol suspension was not applied to a dried film.

Comparative Example 22

The mixed solution containing AD-335AE and MgO as described in Example36 was applied to a saponified ethylene-vinyl alcohol copolymer film(Eval EP-F; product of Kraray Co., Ltd; thickness=15 μm). The Eval layerwas analyzed for the amount of zinc atoms by use of a TEM-EDX, althougha processed-polymer layer comprising the partially neutralized PAAcontaining sodium phosphinate and polyvinyl alcohol was analyzed foramount of zinc atoms by use of a TEM-EDX in other Examples.

Comparative Example 23

The procedure described in Comparative Example 22 was repeated, exceptthat the MgO/ethyl alcohol suspension as described in Example 1 was usedinstead of the mixed solution containing the AD-335AE and MgO. The Evallayer was analyzed, for the amount of zinc atoms by use of a TEM-EDX,although a processed-polymer layer comprising the partially neutralizedPAA containing sodium phosphinate and polyvinyl alcohol was analyzed forthe amount of zinc atoms by use of a TEM-EDX in other Examples.

Comparative Example 24

The procedure described in Example 20 was repeated, except that theMgO/ethyl alcohol suspension was applied to a PET film side instead ofthe polymer layer, the layer being formed of the partially neutralizedPAA containing sodium phosphinate and PO20.

Comparative Example 25

The procedure described in Example 19 was repeated, except that thefollowing conditions were employed. A vapor-deposited MOS-TO film(product of Oike Industrial Co., Ltd.) was used instead of the PET film;and the application of the partially neutralized PAA containing sodiumphosphinate and the PO20 to the deposited MOS-TO film was not performed.

The fabrication conditions and the structure of the laminated filmsdescribed in Examples 19-40 are shown in Table 2. The fabricationconditions and the structure of the laminated films described inExamples 41-58 are shown in Table 3. The fabrication conditions of thelaminated films described in Comparative Examples 11-25 are shown inTable 4. Characteristics of the laminated films are shown in Table 5(Examples 19-50) and in Table 6 (Examples 51-58 and Comparative Examples11-25).

TABLE 2 {circle around (3)} Metal compound/ {circle around (2)} polymerlayer Mixture of metal-compound & resin {circle around (1)} MixingThick- Metal Amount of {circle around (4)} Layer Sub- Ratio ness Heattreatment Metal compound/ appli- Lami- struc- strate Pal*1 (*7) μmconditions*4 compound Resin Resin cation*6 nate ture Ex. 19 PET PO2090/10 2 Pre: 230° C. 30 sec. MgO — — 0.7 g/m² CPP {circle around (1)}{circle around (2)} {circle around (3)} {circle around (4)} Ex. 20 PETPO20 80/20 2 Pre: 230° C. 30 sec. MgO — — 0.7 g/m² CPP {circle around(1)} {circle around (2)} {circle around (3)} {circle around (4)} Ex. 21PET PO20 70/30 2 Pre: 230° C. 30 sec. MgO — — 0.7 g/m² CPP {circlearound (1)} {circle around (2)} {circle around (3)} {circle around (4)}Ex. 22 PET PO20 60/40 2 Pre: 230° C. 30 sec. MgO — — 0.7 g/m² CPP{circle around (1)} {circle around (2)} {circle around (3)} {circlearound (4)} Ex. 23 PET PVA 70/30 2 Pre: 230° C. 30 sec. MgO — — 0.7 g/m²CPP {circle around (1)} {circle around (2)} {circle around (3)} {circlearound (4)} Ex. 24 PET Soluble 80/20 2 Pre: 230° C. 30 sec. MgO — — 0.7g/m² CPP {circle around (1)} {circle around (2)} {circle around (3)}{circle around (4)} starch Ex. 25 PET Sorbitol 80/20 2 Pre: 230° C. 30sec. MgO — — 0.7 g/m² CPP {circle around (1)} {circle around (2)}{circle around (3)} {circle around (4)} Ex. 26 PET Glycerin 60/40 2 Pre:230° C. 30 sec. MgO — — 0.7 g/m² CPP {circle around (1)} {circle around(2)} {circle around (3)} {circle around (4)} Ex. 27 PET PO20 80/20 2Post: 230° C. 30 sec. MgO — — 0.7 g/m² CPP {circle around (1)} {circlearound (2)} {circle around (3)} {circle around (4)} Ex. 28 PET PO2070/30 2 Pre: 160° C. 15 min. MgO — — 0.7 g/m² CPP {circle around (1)}{circle around (2)} {circle around (3)} {circle around (4)} Ex. 29 PETGlycerin 60/40 2 Pre: 160° C. 15 min. MgO — — 0.7 g/m² CPP {circlearound (1)} {circle around (2)} {circle around (3)} {circle around (4)}Ex. 30 PET PO20 80/20 2 Pre: 230° C. 30 sec. Mg(OH)₂ — — 0.7 g/m² CPP{circle around (1)} {circle around (2)} {circle around (3)} {circlearound (4)} Ex. 31 PET PO20 80/20 2 Pre: 230° C. 30 sec. Ca(OH)₂ — — 0.7g/m² CPP {circle around (1)} {circle around (2)} {circle around (3)}{circle around (4)} Ex. 32 PET PO20 80/20 2 Pre: 230° C. 30 sec. ZnO — —0.7 g/m² CPP {circle around (1)} {circle around (2)} {circle around (3)}{circle around (4)} Ex. 33 O-Ny PO20 80/20 2 Pre: 180° C. 30 sec. MgO —— 0.7 g/m² CPP {circle around (1)} {circle around (2)} {circle around(3)} {circle around (4)} Ex. 34 PET PO20 80/20 1 Pre: 230° C. 30 sec.MgO — — 0.7 g/m² CPP {circle around (1)} {circle around (2)} {circlearound (3)} {circle around (4)} Ex. 35 PET PO20 80/20 2 Pre: 230° C. 30sec. MgO — — 0.06 g/m² CPP {circle around (1)} {circle around (2)}{circle around (3)} {circle around (4)} Ex. 36 PET PO20 80/20 2 Pre:230° C. 30 sec. MgO P*2 1/1 0.2 μm CPP {circle around (1)} {circlearound (2)} {circle around (3)} {circle around (4)} Ex. 37 PET PO2080/20 2 Pre: 230° C. 30 sec. MgO P*2 0.5/1   0.2 μm CPP {circle around(1)} {circle around (2)} {circle around (3)} {circle around (4)} Ex. 38PET PO20 80/20 2 Pre: 230° C. 30 sec. MgO P*3 1/1 0.2 μm CPP {circlearound (1)} {circle around (2)} {circle around (3)} {circle around (4)}Ex. 39 PET PO20 80/20 2 Pre: 230° C. 30 sec. MgO P*3 0.5/1   0.2 μm CPP{circle around (1)} {circle around (2)} {circle around (3)} {circlearound (4)} Ex. 40 PET PVA 70/30 2 Pre: 230° C. 30 sec. MgO P*2 1/1 0.2μm CPP {circle around (1)} {circle around (2)} {circle around (3)}{circle around (4)} Pal*1: Polyalcohol, P*2: AD335-AE (polyester-type),P*3: TM-225AE (polyester-type), *4: In Examples 19-27 and 30-40, heattreatment was performed by use of hot-air; and in Examples 28 and 29,heat treatment was performed in a geared oven. In the column of “heattreatment conditions,” the symbol “Pre” refers to the case in which apolymer layer is heat-treated before application of a metallic compound,and the symbol “Post” refers to the case in which a polymer layer isheat-treated after application of a metallic compound. P*5: ZR-133(polyester-type) *6: The unit “g/m²” refers to the amount ofapplication, and the unit “μm” refers to the thickness of application.(*7): poly acrylic acid/polyalcohol

TABLE 3 {circle around (3)} Metal compound/ {circle around (2)} polymerlayer Mixture of metal-compound & resin {circle around (1)} MixingThick- Metal Metal Amount of {circle around (4)} Layer Sub- Ratio nessHeat treatment com- compound/ application*6 Lami- struc- strate Pal*1(*7) μm conditions*4 pound Resin Resin thickness nate ture Ex. 41 PETSoluble 80/20 2 Pre: 230° C. 30 sec. MgO P*2   1/1 0.2 μm CPP {circlearound (1)} {circle around (2)} {circle around (3)} {circle around (4)}starch Ex. 42 PET Sorbitol 80/20 2 Pre: 230° C. 30 sec. MgO P*2   1/10.2 μm CPP {circle around (1)} {circle around (2)} {circle around (3)}{circle around (4)} Ex. 43 PET Glycerin 60/40 2 Pre: 230° C. 30 sec. MgOP*2   1/1 0.2 μm CPP {circle around (1)} {circle around (2)} {circlearound (3)} {circle around (4)} Ex. 44 PET PO20 80/20 2 Pre: 230° C. 30sec. ZnO P*5 1.5/1 0.2 μm CPP {circle around (1)} {circle around (2)}{circle around (3)} {circle around (4)} Ex. 45 PET PO20 80/20 2 Pre:230° C. 30 sec. ZnO P*5 1.5/1 0.1 μm CPP {circle around (1)} {circlearound (2)} {circle around (3)} {circle around (4)} Ex. 46 PET PO2080/20 2 Pre: 230° C. 30 sec. ZnO P*5 1.5/1 0.9 μm CPP {circle around(1)} {circle around (2)} {circle around (3)} {circle around (4)} Ex. 47O-Ny PO20 80/20 2 Pre: 180° C. 15 min. ZnO P*5 1.5/1 0.2 μm CPP {circlearound (1)} {circle around (2)} {circle around (3)} {circle around (4)}Ex. 48 PET PO20 90/10 2 Pre: 230° C. 30 sec. ZnO P*5 1.5/1 0.2 μm CPP{circle around (1)} {circle around (2)} {circle around (3)} {circlearound (4)} Ex. 49 PET PO20 70/30 2 Pre: 230° C. 30 sec. ZnO P*5 1.5/10.2 μm CPP {circle around (1)} {circle around (2)} {circle around (3)}{circle around (4)} Ex. 50 PET PO20 60/40 2 Pre: 230° C. 30 sec. ZnO P*51.5/1 0.2 μm CPP {circle around (1)} {circle around (2)} {circle around(3)} {circle around (4)} Ex. 51 PET PO20 80/20 1 Pre: 230° C. 30 sec.ZnO P*5 1.5/1 0.2 μm CPP {circle around (1)} {circle around (2)} {circlearound (3)} {circle around (4)} Ex. 52 PET PO20 80/20 2 Pre: 160° C. 15min. ZnO P*5 1.5/1 0.2 μm CPP {circle around (1)} {circle around (2)}{circle around (3)} {circle around (4)} Ex. 53 PET Glycerin 60/40 2 Pre:160° C. 15 min. ZnO P*5 1.5/1 0.2 μm CPP {circle around (1)} {circlearound (2)} {circle around (3)} {circle around (4)} Ex. 54 PET PO2080/20 2 Pre: 230° C. 30 sec. Mg(OH)₂ P*2   1/1 0.2 μm CPP {circle around(1)} {circle around (2)} {circle around (3)} {circle around (4)} Ex. 55PET PO20 80/20 2 Pre: 230° C. 30 sec. Ca(OH)₂ P*2   1/1 0.2 μm CPP{circle around (4)} {circle around (1)} {circle around (2)} {circlearound (3)} Ex. 56 PET PO20 80/20 2 Pre: 230° C. 30 sec. ZnO P*5 1.5/10.2 μm CPP {circle around (1)} {circle around (2)} {circle around (3)}{circle around (4)} Ex. 57 PET PO20 80/20 2 Pre: 230° C. 30 sec. ZnO P*51.5/1 0.2 μm PET {circle around (1)} {circle around (2)} {circle around(3)} {circle around (4)} Ex. 58 PET PO20 80/20 2 Pre: 230° C. 30 sec.Application of MgO (0.7 g/m²) CPP {circle around (1)} {circle around(2)} {circle around (3)} {circle around (4)} before application of P*2(0.2 μm) Pal*1: Polyalcohol, P*2: AD335-AE (polyester-type), P*3:TM-225AE (polyester-type), *4: In Examples 19-27 and 30-40, heattreatment was performed by use of hot-air; and in Examples 28 and 29,heat treatment was performed in a geared oven. In the column of “heattreatment conditions,” the symbol “Pre” refers to the case in which apolymer layer is heat-treated before application of a metallic compound,and the symbol “Post” refers to the case in which a polymer layer isheat-treated after application of a metallic compound. P*5: ZR-133(polyester-type) *6: The unit “g/m²” refers to the amount ofapplication, and the unit “μm” refers to the thickness of application.(*7): poly acrylic acid/polyalcohol

TABLE 4 {circle around (3)} Metal compound/ {circle around (2)} polymerlayer Mixture of metal-compound & resin {circle around (1)} PAA Thick-Metal Metal Amount of {circle around (4)} Layer Sub- content ness Heattreatment com- compound/ appli- Lami- struc- strate Pal*1 % μmconditions*4 pound Resin Resin cation*6 nate ture Co. PET PO20 90 2 Pre:230° C. 30 sec. — — — — CPP {circle around (1)} {circle around (2)}{circle around (4)} Ex. 11 Co. PET PO20 80 2 Pre: 230° C. 30 sec. — — —— CPP {circle around (1)} {circle around (2)} {circle around (4)} Ex. 12Co. PET PO20 70 2 Pre: 230° C. 30 sec. — — — — CPP {circle around (1)}{circle around (2)} {circle around (4)} Ex. 13 Co. PET PO20 60 2 Pre:230° C. 30 sec. — — — — CPP {circle around (1)} {circle around (2)}{circle around (4)} Ex. 14 Co. PET Sorbitol 80 2 Pre: 230° C. 30 sec. —— — — CPP {circle around (1)} {circle around (2)} {circle around (4)}Ex. 15 Co. PET Glycerin 60 2 Pre: 230° C. 30 sec. — — — — CPP {circlearound (1)} {circle around (2)} {circle around (4)} Ex. 16 Co. PETSoluble 80 2 Pre: 230° C. 30 sec. — — — — CPP {circle around (1)}{circle around (2)} {circle around (4)} Ex. 17 starch Co. PET PVA 70 2Pre: 230° C. 30 sec. — — — — CPP {circle around (1)} {circle around (2)}{circle around (4)} Ex. 18 Co. PET PO20 70 2 Pre: 160° C. 15 min. — — —— CPP {circle around (1)} {circle around (2)} {circle around (4)} Ex. 19Co. PET Glycerin 60 2 Pre: 160° C. 15 min. — — — — CPP {circle around(1)} {circle around (2)} {circle around (4)} Ex. 20 Co. O-Ny PO20 80 2Pre: 180° C. 15 min. — — — — CPP {circle around (1)} {circle around (2)}{circle around (4)} Ex. 21 Co. EVOH — — — — ZnO P*5 1.5/1 0.2 μm CPP{circle around (1)} {circle around (3)} {circle around (4)} Ex. 22 Co.EVOH — — — — MgO — — 0.7 g/m² CPP {circle around (1)} {circle around(3)} {circle around (4)} Ex. 23 Co. PET PO20 80 2 Pre: 230° C. 30 sec.MgO — — — CPP {circle around (3)} {circle around (1)} {circle around(2)} Ex. 24 Co. PET — — — — SiOx — — — CPP {circle around (1)} {circlearound (2)} {circle around (4)} Ex. 25 Pal*1: Polyalcohol, P*2: AD335-AE(polyester-type), P*3: TM-225AE (polyester-type), *4: In Examples 19-27and 30-40, heat treatment was performed by use of hot-air; and inExamples 28 and 29, heat treatment was performed in a geared oven. Inthe column of “heat treatment conditions,” the symbol “Pre” refers tothe case in which a polymer layer is heat-treated before application ofa metallic compound, and the symbol “Post” refers to the case in which apolymer layer is heat-treated after application of a metallic compound.P*5: ZR-133 (polyester-type) *6: The unit “g/m²” refers to the amount ofapplication, and the unit “μm” refers to the thickness of application.(*7): poly acrylic acid/polyalcohol

TABLE 5 Oxygen Water Existence Permeability resis- Ra (μm) ratio ofmetal Pre*8 Post*9 tance AFM TEM compound Ex. 19 0.2 0.2 O 0.015 0.061.56 Ex. 20 <0.1 <0.1 O 0.015 0.06 1.56 Ex. 21 0.2 <0.1 O 0.015 0.061.56 Ex. 22 <0.1 0.4 O 0.015 0.06 1.56 Ex. 23 0.2 0.2 O 0.015 0.06 1.56Ex. 24 0.2 <0.1 O 0.015 0.06 1.56 Ex. 25 0.1 0.1 O 0.015 0.06 1.56 Ex.26 0.2 0.5 O 0.015 0.06 1.56 Ex. 27 <0.1 <0.1 O 0.015 0.06 1.56 Ex. 280.6 3.9 O 0.015 0.06 2.50 Ex. 29 0.1 0.2 O 0.015 0.06 2.50 Ex. 30 0.40.9 O 0.019 0.06 1.56 Ex. 31 1.0 0.9 O 0.019 0.06 1.56 Ex. 32 0.9 0.2 O0.019 0.06 1.56 Ex. 33 4.3 <0.1 O 0.015 0.06 2.50 Ex. 34 <0.1 <0.1 O0.015 0.06 1.56 Ex. 35 1.4 3 O 0.015 0.06 1.56 Ex. 36 <0.1 <0.1 O 0.0030.02 1.56 Ex. 37 <0.1 1.2 O 0.003 0.02 1.56 Ex. 38 <0.1 0.2 O 0.003 0.021.56 Ex. 39 <0.1 <0.1 O 0.003 0.02 1.56 Ex. 40 0.2 0.2 O 0.003 0.02 1.56Ex. 41 <0.1 <0.1 O 0.003 0.02 1.56 Ex. 42 <0.1 3.5 O 0.003 0.02 1.56 Ex.43 0.2 0.5 O 0.003 0.02 1.56 Ex. 44 0.3 0.1 O 0.003 0.02 1.56 Ex. 45 0.30.1 O 0.003 0.02 1.56 Ex. 46 0.4 0.1 O 0.003 0.02 1.56 Ex. 47 4.3 <0.1 O0.003 0.02 2.50 Ex. 48 0.5 0.1 O 0.003 0.02 1.56 Ex. 49 0.3 0.1 O 0.0030.02 1.56 Ex. 50 0.3 0.2 O 0.003 0.02 1.56 Pre *8): Measurement beforeretort treatment Post *9): Measurement after retort treatment

TABLE 6 Oxygen Water Existence Permeability resis- Ra (μm) ratio ofmetal Pre*8 Post*9 tance AFM TEM compound Ex. 51 0.3 0.1 O 0.003 0.021.56 Ex. 52 0.6 4.0 O 0.003 0.02 2.50 Ex. 53 0.2 0.2 O 0.003 0.02 2.50Ex. 54 0.4 0.9 O 0.004 0.02 1.56 Ex. 55 0.5 1.0 O 0.004 0.02 1.56 Ex. 560.3 1.0 O 0.003 0.02 1.56 Ex. 57 0.3 1.0 O 0.003 0.02 1.56 Ex. 58 <0.1<0.1 O 0.003 0.02 1.56 Comp. 13 50 O — — 0 Ex. 11 Comp. 1.0 14 O — — 0Ex. 12 Comp. 0.5 20 O — — 0 Ex. 13 Comp. 0.9 40 O — — 0 Ex. 14 Comp. 3.514 O — — 0 Ex. 15 Comp. 40 100 O — — 0 Ex. 16 Comp. 1.0 14 O — — 0 Ex.17 Comp. 0.4 15 O — — 0 Ex. 18 Comp. 122 140 O — — 0 Ex. 19 Comp. 77 130O — — 0 Ex. 20 Comp. 30 110 O — — 0 Ex. 21 Comp. 6.2 47 O 0.003 0.02 0Ex. 22 Comp. 5.9 47 O 0.015 0.06 0 Ex. 23 Comp. 1.0 14 O 0.015 0.02 0Ex. 24 Comp. 1.0 14 O 0.001 0.0004 0 Ex. 25 Pre*8): Measurement beforeretort treatment Post*9): Measurement after retort treatment

INDUSTRIAL APPLICABILITY

When a metallic compound is applied to a polymer layer, the producedfilm exhibits excellent gas-barrier properties. Application of ametallic compound is carried out through a simple, convenient, andinexpensive process as compared with the deposition process. When apolymer layer is heat-treated, water resistance is imparted to thelayer, and thus a gas-barrier film exhibiting water resistance andexcellent oxygen gas-barrier properties can be produced, and the gasbarrier properties of the film are not impaired through washing withwater.

What is claimed is:
 1. A gas-barrier film comprising (i) a polymer layerformed of a mixture of polyalcohol and at least one poly(meth)acrylicacid polymer selected from the group consisting of poly(meth)acrylicacids and partially neutralized poly(meth)acrylic acids, and (ii) ametallic-compound-containing layer on a surface of the polymer layer,wherein the metallic-compound-containing layer exhibits a mean surfaceroughness (Ra) of between 0.003-0.019 μm as measured by atomic forcemicroscope (AFM).
 2. A gas-barrier film according to claim 1, whereinthe metallic-compound-containing layer is continuous.
 3. A gas-barrierfilm according to claim 1, wherein the metallic-compound-containinglayer is discontinuous.
 4. A gas-barrier film according to claim 1,wherein the polymer layer is fixed onto a surface of a substrate suchthat said polymer layer is disposed between the substrate and themetallic-compound-containing layer.
 5. A gas-barrier film according toclaim 1, wherein at least the polymer layer is subjected to heattreatment.
 6. A gas-barrier film according to claim 1, wherein themetallic-compound-containing layer includes a mixture of the metalliccompound and a resin.
 7. A sterilization process which comprises boilingor retorting food packaged with the gas-barrier film according toclaim
 1. 8. A gas-barrier film comprising (i) a polymer layer formed ofa mixture of polyalcohol and at least one poly(meth)acrylic acid polymerselected from the group consisting of poly(meth)acrylic acids andpartially neutralized poly(meth)acrylic acids, and (ii) ametallic-compound-containing layer on a surface of the polymer layer,wherein the metallic compound is oxides, hydroxides, or carbonates of atleast one species of metal selected from the group consisting ofmagnesium, calcium, and zinc, and wherein themetallic-compound-containing layer exhibits a mean surface roughness(Ra) of between 0.003-0.03 μm as measured by atomic force microscope(AFM).
 9. A gas-barrier film according to claim 8, wherein themetallic-compound-containing layer exhibits Ra of between 0.003-0.02 μmas measured by AFM.
 10. A gas-barrier film according to claim 8, whereinthe metallic-compound-containing layer is continuous.
 11. A gas-barrierfilm according to claim 8, wherein the metallic-compound-containinglayer is discontinuous.
 12. A gas-barrier film according to claim 8,wherein the polymer layer is fixed onto a surface of a substrate suchthat said polymer layer is disposed between the substrate and themetallic-compound-containing layer.
 13. A gas-barrier film according toclaim 8, wherein at least the polymer layer is subjected to heattreatment.
 14. A gas-barrier film according to claim 8, wherein themetallic compound-containing layer includes a mixture of the metalliccompound and a resin.
 15. A sterilization process which comprisesboiling or retorting food packaged with the gas-barrier film accordingto claim
 8. 16. A method of making a gas-barrier film comprisingapplying a metallic-compound-containing material onto a surface of apolymer layer by coating, spraying, powdering, or dipping to form ametallic-compound-containing layer which exhibits a mean surfaceroughness (Ra) of between 0.003-003 μm as measured by atomic forcemicroscope(AFM), wherein said polymer layer is formed of a mixture ofpolyalcohol and at least one poly(meth)acrylic acid polymer selectedfrom the group consisting of poly(meth)acrylic acids and partiallyneutralized poly(meth)acrylic acids, and wherein the metallic compoundis oxides, hydroxides, or carbonates of at least one species of metalselected from the group consisting of magnesium, calcium, and zinc. 17.The method of claim 16, wherein applying themetallic-compound-containing material comprises spraying a metalliccompound or a suspension of a metallic compound and a resin onto thepolymer layer surface.
 18. The method of claim 16, wherein applying themetallic-compound-containing material comprises coating a metalliccompound or a suspension of a metallic compound and a resin onto thepolymer layer surface.
 19. The method of claim 16, wherein applying themetallic-compound-containing material comprises spraying a powdercontaining a metallic compound onto the polymer layer surface.